As a techie who actually has Google Fiber, it's been amazing. The first couple weeks were really rocky--random internet outages which were unexplainable.
They sent a tech out, who'd never seen anything like it, and he's like "well, I guess I'll replace the network box, because I have no idea what it is." Worked great ever since.
The only major disadvantage is they don't want you running your own router, and have actually hassled me for doing so. They offer just a fiber jack to businesses, but don't offer it for residential customers. Residential customers HAVE to use their "network box" (router). There are actually howtos on the internet of plugging into the fiber jack, if you have a managed switch and set the VLAN tags right.
I get 400 Mbit up/down over wireless (my own router)
I get 900 Mbit up/down wired
Speeds are constant, regardless of time of day, and no weird latency issues at all. I get a reliable 1ms ping to a friend who also has Google Fiber 15mi away, and I get very low pings to the rest of the world. It's hands down the best internet I've ever had. Customer service is friendly, too.